Plant growing systems are known that comprise a light source for supplying artificial light to a plant being grown in the plant growing system. The light source facilitates growth of the plant during periods when low levels of natural light are available, for example, due to seasonal variations in natural light levels.
WO 2013/089825 discloses a device having a light source for assisting growth of a plant, wherein the power consumption of the light source is varied according to the electricity rate. The power consumption of the light source is increased when the electricity rate is low to reduce the cost of growing the plant. However, this can result in the growth of the plant being accelerated such that it matures and is ready for harvest at a time when there is already an abundance of that type of plant on the market, in which case the plant is superfluous to requirements and may be wasted.
US 2005/0252078 discloses a method and system for optimising plant production in a cost effective manner. The system comprises a processor that controls resources such as lighting and carbon dioxide. The processor receives a desired plant production rate and determines amounts of each resource to expend consistent with plant production goals and resource costs.